Method for conserving water



United States Patent US. Cl. 21-605 7 Claims ABSTRACT OF THE DISCLOSUREMethod of inhibiting the evaporation of water from a water containingsurface by contacting the surface in powdered form with a urea complexformed from urea and a C C hydrocarbylamine or acid or the correspondinghydroxy-substituted hydrocarbyl-amine or acid and forming asubstantially monomolecular layer of the hydrocarbyl compound thereon.

This application is a continuation-in-part of our copending applicationSer. No. 127,810, filed July 31, 1961, now abandoned.

This invention relates to a method for inhibiting the evaporation ofwater, and in its more specific aspect to a method for conserving waterin reservoirs and/or soil by applying a water vapor barrier filmthereto. In one aspect, this invention relates to a method of preparinga material which upon application to the reservoir or soil water forms awater vapor barrier film thereon that inhibits the evaporation of watertherefrom.

In many geographical areas, particularly arid or semiarid regions whereadequate sources of water are limited or lacking altogether,conservation of Water is of major importance. The present invention inan object is directed to a method for conserving water in reservoirs bypreparing a hydrocarbon compound of prescribed type-urea complex of afilm-forming material exhibiting vapor-inhibiting properties, andcontacting the water with the formed complex whereby the complexdissociates and the water vapor inhibiting film is formed on the watersurface.

In another aspect the invention is directed to a method of conservingwater in soil and concomitantly providing nitrogen values thereto tostimulate the growth of plants and crops therein. This object is alsoattained by contacting the soil with the complex. The complexdissociates on coming in contact with the soil water and forms a barrierfilm in the soil which inhibits the evaporation of water containedtherein. In addition, dissociation of the complex provides nitrogenvalues in the form of urea to the soil.

In accordance with our invention, there is applied to the reservoir and/or the soil water a film-forming agent or material which has beencomplexed with urea and subsequently dissociates upon contact with thereservoir water or the water in the soil to form a water vaporinhibitingfilm. The water vapor barrier film-forming agent comprises asubstantially hydrophobic aliphatic hydrocarbon compound, having thegeneral formula R-A, wherein A is a member selected from the groupconsisting of NH and COOH, and R is a hydrocarbyl or a hydroxysubstituted hydrocarbyl radical containing 13 to 20 carbon atomstherein, said compound being capable of forming a complex with urea andpossessing a polar group exhibiting an aflinity for water, as describedmore fully hereinafter.

The complex is formed by dissolving or dispersing the aliphatichydrocarbon compound in a suitable liquid sol- 3,441,369 Patented Apr.29, 1969 vent, preferably a non-aqueous solvent. The resulting solutionor dispersion of the hydrocarbon compound is brought into contact withurea dissolved in a polar solvent and there is formed a solidurea-aliphatic hydrocarbon compound complex which is readily separatedfrom the solvent. It is preferable to employ a saturated solution of thecomplexing agent, e.g. urea, in a polar solvent. The resulting solidcomplex is recovered from the remaining solution as by filtering,centrifuging, or the like, and the complex may be washed, dried andrecovered in finely divided or powder form. The complex can then bebrought into contact with the water in the reservoir or the soilpreferably by applying the solid or powdered complex to the water orsoil surface or mixing it therewith so that it contacts the watertherein to dissociate the complex. The aliphatic hydrocarbon compound oncontact with the water in the reservoir or soil is released from thecomplex and forms a barrier film which is usually in the form of amonomolecular layer. Water acting on the polar group, or hydrophilicportion, of the aliphatic hydrocarbon compound results in the desiredspreading of the material, and the hydrophobic portion causes themonomolecular layer to form on the surface of the water.

In the event that the soil is relatively water-free little if anydissociation of the complex takes place. However, when the soil becomesmoist with water, such as by precipitation or irrigation, the complexdissociates and supplies the barrier film and nitrogen to the soil.

The aliphatic hydrocarbon compounds found suitable for our inventionmust have a straight chain portion at least between 13 and 20 carbonatoms, and, in addition, must be capable of forming a complex with thecomplexing agent, e.g. urea. In addition the aliphatic hydrocarboncompound although substantially hydrophobic must contain a polar NH or aCOOH group, preferably a terminal polar group, exhibiting an aflinityfor water. The straight chain portion of the aliphatic hydrocarboncompound may be saturated or olefinically unsaturated. Representativealiphatic hydrocarbon compounds of prescribed type include fatty acids,such as myristic and palmitic acid, stearic acid, arachidic acid,hydroxystearic acid, oleic acid and linoleic acid, the aliphatic fattyamines, hexadecylamine and octadecylamine and mixtures of the fattyacids and amines. The present invention is particularly advantageous inthat it permits the use of commercially available mixtures of aliphaticfatty acids which are particularly attractive for use in waterconservation because of their relatively low cost.

When the hydrocarbon compound is a solid at room temperature andatmospheric pressure, the compound is dissolved initially in a liquidsolvent which desirably includes the various normally liquid petroleumhydrocarbons or petroleum fractions in the naphtha boiling range, suchas petroleum hydrocarbons having a boiling point or range of from aboutto 425 F. Aromatic hydrocarbons, for example, benzene, toluene andxylenes, are preferred. The liquid solvent should be substantiallydevoid of those compounds or hydrocarbons which form a complex with ureaunder the conditions of complex formation or complex dissociation.

It is Well recognized that a number of aliphatic hydrocarbon compounds,upon treatment with urea, or its analogs e.g. thiourea, form a complex,often a solid, crystalline complex. In practicing our invention, thecomplexing agent consisting of urea is initially dissolved in a polarsolvent, e.g. an alcohol, which is then mixed with a solution of thealiphatic hydrocarbon compound of prescribed type from the complex. Theformed complex can be separated from the solution and may be recoveredby any suitable means, such as filtering, decanting, centrifuging, orthe like. The complexing action desirably occurs at a temperature in therange of from about 40 F, to 125 F., although higher temperatures may beemployed depending to some extent upon the melting point of eachcomponent making up the mixture.

The complex containing the film-forming agent is contacted with, oradded directly to, the surface of the water and/ or soil or admixedtherein in the form of a fine powder or aerosol. The complex, uponcontact with the water, dissociates thereby releasing the aliphatichydrocarbon compound which spreads as a thin film over the water. Theurea portion of the complex applied to the soil serves as a source ofnitrogen to the soil.

Suitable polar solvents in which the urea complexing agent is dissolvedinclude the normally liquid polar aliphatic organic compounds. Theseinclude, for example, the alkanols, such as methanol, ethanol, propanol,isopropanol, isobutanol, n-butanol, tertiary butyl alcohol; the variousketones, such as acetone, methylethyl ketone,

finely powdered complex product was obtained. In one example, 5% byweight Cab-O-Sil, an anti-caking agent, was thoroughly admixed with thedried solid complex.

Several series of tests were conducted to evaluate the vapor-inhibitingproperties of the aliphatic hydrocarbon compound of prescribed type. Thepowdered complex in an amount of 50 milligrams was dusted onto thesurface of 400 milliliters of deionized water contained in an 800milliliter beaker. The beakers were weighed to the nearest gram, andallowed to stand uncovered at ambient temperature. Thereafter, thebeakers were weighed at approximately 24 hour intervals The loss inweight was taken as the amount of water evaporation. For each series oftests, there was provided as a Control a beaker of water having nofilm-forming agent added thereto.

The following table shows the results of the tests. The data indicatethe cumulative amount in grams of water evaporation from each beaker.

TAB LE .EVAPO RATION TESTS Wt. (grams) of water evaporated Percentreduction After Over Control Example Material 1 day 2 days 5 days 1 day2 days 5 days Series I:

l Control A 21 37 72 2 Octadecylarnine-urea- 14 26 55 33. 3 29. 7 23. 6

complex. 3 Stearic acid-urea complex- 15 28 59 28. 5 24. 3 18.0 SeriesII:

4 Control B 35 60 5 Myristic acid-urea 15 28 53 20 11. 7

complex. 6 Palmityl amine-urea 15 28 49 25 20 18. 3

complex. 7 Ex. 5 complex plus 5% 17 30 55 15 14. 3 8.4

Mierocil. 8 Ex. 6 complex plus 5% 19 31 54 5 11.4 10

Mierocil.

1 Measured after 4 days.

ethylpropyl ketone, methyl propyl ketone, methyl n-butyl ketone,methylisobutyl ketone; aqueous solutions of the foregoing; and water. Ingeneral, any normally liquid polar aliphatic organic compound containingfrom 1 to 6 carbon atoms per molecule can suitably be employed. Otherpolar solvents which may suitably be employed include the low boilingamines such as ethylamine; the low boiling mercaptans such as ethylmercaptan; the olefinic glycols, such as monoethylene glycol; thealkanolamines, such as ethanolamine; or mixtures thereof, such as anaqueous solution of methanol and monoethylene glycol.

Where deemed desirable, a small amount of a microdimensional silicapowder or alumina powder which are hydrophilic may be incorporated inthe powdered complex product. The amount of silica or alumina powderused depends somewhat upon the hydrocarbon derivative being treated, butgenerally about 0.5 to 10% by weight is satisfactory. Themicrodimensional powder serves as an anti-caking agent to assist inmaintaining the complex in a substantially dry state and makes itfree-flowing Suitable microdimensional powders include a finely powderedsilica sold under the Trade name Cab-O-Sil and a finely powdered aluminasold under the Trade name Alon C.

In the following examples which further illustrate our invention, acomplex of the aliphatic hydrocarbon compound was prepared according tothe following procedure:

For each example, 56 grams of the aliphatic hydrocarbon compound to becomplexed with urea was dissolved in 750 milliliters of benzene. Asaturated solution of urea in methanol was prepared, and 500 millilitersof this solution was added to the benzene solution containing thehydrocarbon derivative at about 80 F. with vigorous stirring. Themixture was stirred for about 15 minutes, and the resulting solidcomplex was separated from the remaining solution by filtration with aBuchner funnel. The solid complex was washed several times with 5 0milliliter portions of pentane and permitted to air dry. A

2 Anti-caking agent It will be observed from the table that thematerials tested provided an effective vapor barrier film wherebyevaporation of water was inhibited. Thus, the method provided inaccordance with our invention offers an effective means in forming avapor-inhibiting film on the exposed surface of the water.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations may be made as areindicated in the appended claims.

We claim:

1. Method of inhibiting the evaporation of water from a surface thereofwhich comprises contacting said surface with a urea complex comprisingurea and a hydrocarbon compound having the general formula RA, wherein Ais a member selected from the group consisting of NH and COOH, and R isa member selected from the group consisting of a hydrocarbyl radical anda hydroxy-su-bstituted hydrocarbyl radical containing from 13 to 20carbon atoms therein, said complex being applied in powdered form tosaid water surface and forming a substantially monomolecular layer ofsaid hydrocarbon compound thereon.

2. The method of claim 1 wherein said hydrocarbon compound is stearicacid.

3. The method of claim 1 wherein said hydrocarbon compound isoctadecylamine.

4. The method of claim 1 wherein said hydrocarbon compound is a mixtureof a fatty acid and a fatty amine.

5. The method of claim 1 wherein said hydrocarbon compound is a mixtureof fatty acids.

6. The method of claim 1 wherein said complex has admixed therewith fromabout 0.5 to about 10% by weight of a finely-divided anti-caking agentselected from the group consisting of alumina powder and silica powder.

7. The method of claim 1 wherein said surface is soil.

(References on following page) 5 6 References Cited E. P. Whitlow eta1.: Proceedings of Eighteenth An- UNITED STATES PATENTS nual WaterConference, Engineers Society of Western P 3,146,059 8/1964 Suzuki et a121 6 o.s ennsylvama PP 41 46 Otber1957 OTHER REFERENCES 5 MORRIS O.WOLK, Primary Examiner.

Fieser et al.: Advanced Organic Chemistry, 131-133, SIDNEY M ARANTZ,Assistant Examiner Reinhold Publishing Corp., New York, 1961.

Reservoir Evaporation Reduction Through the Use CL of MonomoiecularLayers, a paper presented to American Water Works Association by Timblinet al., pp. 1, 10 260-965 10-11, September 1957.

